Small $x$ resummation of photon impact factors and the $γ^* γ^*$ high energy scattering

Fuente: arXiv
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Main Author: Colferai, Dimitri
Format: Preprint
Published: 2025
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author Colferai, Dimitri
author_facet Colferai, Dimitri
contents I present the renormalization group improved collinear resummation of the photon-gluon impact factors. We construct the resummed cross section for virtual photon-photon ($γ^*γ^*$) scattering which incorporates the impact factors and BFKL gluon Green's function up to the next-to-leading logarithmic accuracy in energy. The impact factors include important kinematical effects which are responsible for the most singular poles in Mellin space at next-to-leading order. Further conditions on the resummed cross section are obtained by requiring the consistency with the collinear limits. Our analysis is consistent with previous impact factor calculations at NLO, apart from a new term proportional to $C_F$ that we find for the longitudinal polarization. Finally, we use the resummed cross section to compare with the LEP data on the $γ^*γ^*$ cross section and with previous calculations. The resummed result is lower than the leading logarithmic approximation but higher than the pure next-to-leading one, and is consistent with the experimental data.
format Preprint
id arxiv_https___arxiv_org_abs_2503_10188
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Small $x$ resummation of photon impact factors and the $γ^* γ^*$ high energy scattering
Colferai, Dimitri
High Energy Physics - Phenomenology
I present the renormalization group improved collinear resummation of the photon-gluon impact factors. We construct the resummed cross section for virtual photon-photon ($γ^*γ^*$) scattering which incorporates the impact factors and BFKL gluon Green's function up to the next-to-leading logarithmic accuracy in energy. The impact factors include important kinematical effects which are responsible for the most singular poles in Mellin space at next-to-leading order. Further conditions on the resummed cross section are obtained by requiring the consistency with the collinear limits. Our analysis is consistent with previous impact factor calculations at NLO, apart from a new term proportional to $C_F$ that we find for the longitudinal polarization. Finally, we use the resummed cross section to compare with the LEP data on the $γ^*γ^*$ cross section and with previous calculations. The resummed result is lower than the leading logarithmic approximation but higher than the pure next-to-leading one, and is consistent with the experimental data.
title Small $x$ resummation of photon impact factors and the $γ^* γ^*$ high energy scattering
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2503.10188